ComputingConfidence

Howto extract the sound track from a Youtube flv (FLash Video) using VLC media player.

It it not always successful to use a method that just copy the sound track from the flv, because of varying coding schemes in the original track.
A more universal solution is to stream the sound output to a new freshly coded file.  Unless you have many files you want to process, I will suggest to use VLC Media Player.

I have used VLC on Ubuntu GNU/Linux with a great deal of success.  The advantage is that if you can play play the video and hear the sound, then you should be able to stream/code a new separate soundtrack in any format you have installed coding libraries for.  Coding of mp3 is not available in a new Ubuntu installation, but is only a few commands away, look at the Ubuntu help pages.

There are loads of fancy ways to get hold of the flv file in the first place. Personally I just copy the /tmp/flv?????? to for example ~/video/flv/niceYoutubeVideo.flv or something like that.  I normally use mc (Midnight Commander).

Now to the sound extract:

• Open VLC media player
• [Media] [Convert / Save] or Ctrl-R
• Enter input file location/name/extension (the flv file to extract from)
  
• Clock [Convert / Save]
• Select [File] as output and provide file location/name/extension (.mp3)
  
• Select Encapsulation [RAW]
• In the [Video codec] tab check that [Video] is not selected.
• In the [Audio codec] select [Audio], set [Codec] to for example [MP3], adjust bitrate etc.
• Click [Save] or Alt-S

Now extract should be in progress

Take care to choose a sensible bit rate for the sound file.  In most cases it is best to choose the same bit rate as the original sound track has.

Have fun.